1. Field of the Invention
The present invention relates generally to a caliper of a disc brake device mainly used for an automobile, and particularly to a support mechanism for slidably supporting the caliper by means of a slide pin. More particularly, the invention relates to a mechanism for a rotation-preventing structure of a divided pin in a caliper support mechanism of the disc brake of the type in which a slide pin is fastened to the caliper by means of a bolt, whereby the squeezing of the slide pin by the support bracket is remarkably reduced, the slide pin is smoothly slidable within the pin guide hole of the support bracket, and the drag of the brake and the squeak of the brake are remarkably reduced.
2. Related Art
A disc brake of the type in which the caliper is slidably supported by the slide pin, and the slide pin is fixed to a lug of the caliper by means of a bolt is known. Such a structure that a stepped portion is formed in the lug of the caliper in order to stop the turn of the slide pin which otherwise would be turned together with the bolt when the bolt is screwed into the threaded hole of the end face of the slide pin and tightened thereto, and the flat side of a head of the slide pin is brought into contact with the end face of the stepped portion, thereby stopping the turn of the slide pin, is also known as disclosed in Post-examined Japanese Utility Model Publication No. Sho. 61-21619.
The conventional art will briefly be described with reference to FIGS. 4 to 6.
A bolt 9 is inserted into a bolt hole 10 of a lug 5C of a caliper 5. A flat side 8B of a head 8A of a slide pin 8 is brought into contact with the end face of a stepped portion 11 of the lug, to thereby stop the turn of the slide pin. The bolt 9 is screwed into a screw hole 8C of the end face of the slide pin 8 and tightened thereto, so that the slide pin 8 is fixed to the lug 5C. The slide pin 8 is slidably inserted into a pin guide hole 7 of a support bracket 1, whereby the support bracket 1 slidably supports the caliper 5.
The stepped portion 11 is formed in the lug 5C of the caliper 5. The head 8A is bevelled to have flat sides 8B. The flat side 8B is brought into contact with the end face of the stepped portion 11, to thereby prevent the turn of the slide pin 8. The end face of the stepped portion is arcuately incurred in cross section.
In the disc brake of the type in which the caliper is slidably supported by the slide pin, the pin type disc brake, under a braking force, the brake pad pushes the support brackets outwardly when viewed horizontally. The support bracket is slightly bent aside in the braking direction, by the pushing force of the brake pad. As the deflection of the support bracket, the pin guide hole of the support bracket is displaced with respect to the slide pin. By the displacement of the pin guide hole, the sliding resistance of the slide pin increases, thereby hindering a smooth motion of the slide pin within the pin guide hole. The wear of the slide pin is promoted, so that the durability thereof is reduced and a resistance to the returning motion of the caliper increases. Drag of the brake and the squeak of the brake take place. An additional problem of the conventional art is that much and care work is required for arcuately curving inward the end face of the stepped portion of the lug of the caliper.